DTC 4-3-6 Rear Heated Oxygen Sensor Compensation

4-3-6 REAR HEATED OXYGEN SENSOR, COMPENSATION

Preconditions for DTC
^ The Rear Heated Oxygen Sensor (HO2S) constantly monitors the front HO2S and its short term fuel trim so that it matches the exhaust gas oxygen content. If the short term fuel trim differs, the rear HO2S makes fine adjustments to it. When this adjustment is excessive, the ECM interprets this as a fault with the front HO2S and DTC 4-3-6 is set.

Substitute value
^ Fuel trim shut off.

Fault sources
^ Uneven compression.
^ Air leakage in the intake system.
^ Air leakage in the exhaust system.
^ Defective rear HO2S.
^ Defective front HO2S.

Fault symptoms
^ May result in poorer performance.